Extracellular polymeric substance (EPS) is the description of a glycocalyx that is a component of a biofilm.

Flagella

Flagella are relatively long filamentous
appendages consisting of a filament, hook, and basal body.

Prokaryotic flagella rotate to push the
cell.

Motile bacteria exhibit taxis; positive
taxis is movement toward an attractant, and negative taxis is movement away
from a repellent.

Arrangement
of Bacterial Flagella

The
Structure of a Prokaryotic Flagellum

Flagella
are anchored by pairs of rings associated with the plasma membrane
and cell wall. Gram positive bacteria have only the inner pair of
rings.

The filament
is composed of the globular protein flagellin, which is arranged in
several intertwined chains that form a helix around a hollow core.

Flagellin
can vary in structure and is used to identify some pathogenic bacteria
serologically. The flagellar antigens are referred to as H antigens.

E. coli may express any of at least 50 different variants;
serovars (serological variants) identified as O157:H7 are associated
with food borne epidemics (O antigens are somatic antigens and are
lipopolysaccharide complexes associated with the cell wall).

Flagella
and Bacterial Motility

Axial Filaments

Spiral cells that move by means of an axial
filament (endoflagellum) are called spirochetes.

Axial filaments are similar to flagella,
except that they wrap around the cell.

Axial
filaments

Fimbriae And Pili

Fimbriae and pili are short, thin appendages.

Cells may have many fimbriae, which help
the cells adhere to surfaces.

Cells
that have pili have only one or two.

Pili join cells either for the transfer
of DNA from one cell to another (sex pili) or are used for special types
of movement; twitching, seen in Pseudomonas aeurginosa, Neisseria
gonorrhoeae and some strains of E. coli, or the gliding motility of myxobacteria.